1. Field of the Invention
This invention relates generally to an improved image recording apparatus and, more particularly, to an improved image recording apparatus having an adjustable mask for selectively controlling image line resolution in a simple and economical manner.
2. Description of the Prior Art
Image recording apparatus of the type responsive to electrical signal input information representative of a select image for recording that image by exposing a photosensitive material are well known in the art. Such recording may be made by affecting a relative movement between a photosensitive recording medium and a row of light emitting elements such as light emitting diodes (LEDs). The row of light emitting elements operates to expose a line of points representing one line of the image as the photosensitive material is moved in a transverse direction relative to the exposed line, in a manner as disclosed in U.S. Pat. No. 4,090,206, entitled "Method and Apparatus for Producing Successive Lines of Image Points on a Recording Medium", by Josef Pfeifer, issued May 16, 1978. In the aforementioned image recording apparatus there is also provided a means to oscillate the line of light exposing elements in a direction transverse to the direction of relative movement between the light exposing elements and the photosensitive recording medium so as to displace each light emitting element by a distance at least equal to the spacing between adjacent light emitting elements. In this manner, the surface of the photosensitive material directly opposite the spaces between adjacent light emitting elements may be exposed without the provision of additional light emitting elements. In order to improve the resolution of each line, each light emitting element or LED of the aforementioned reference is optically coupled to a scale reducing projector lens. The scale reducing projector lenses, however, must also be oscillated in unison with the light emitting diodes thereby substantially complicating and increasing the weight of the mechanism that must be oscillated.
U.S. Pat. No. 4,378,149, entitled "High Speed Low-Cost Character Printer", by Peter R. Ebner, issued Mar. 29, 1983 shows an LED array of light emitting elements positioned adjacent to apertured masks which have cross-sectional areas substantially smaller than the cross-sectional areas of the LEDs to provide an improvement in the character resolution obtainable. Although such light transmitting apertures may be utilized in place of the aforementioned projector lenses to affect a reduction in the width of the image points to be formed along the line of exposure, such light transmitting apertures nevertheless would still have to be oscillated in unison with the row of spaced apart light emitting elements thereby also further complicating the oscillating structure.
Therefore, it is a primary object of this invention to provide an image recording apparatus of the type having a plurality of spaced apart light emitting elements arranged in a line with an improved masking arrangement in which the width of the exposed line of image points may be adjusted to control image resolution.
It is a further object of this invention to provide an image recording apparatus of the type having a line of spaced apart light emitting elements which may be oscillated to expose areas between the light emitting elements which would otherwise be unexposed together with a variable masking means in which the width of the line of spaced apart image points may be controlled to thereby improve image resolution.
Other objects of the invention will be in part obvious and will in part appear hereinafter. The invention accordingly comprises a mechanism and system possessing the construction, combination of elements and arrangement of parts which are exemplified in the following detailed disclosure.